Balloons are used for many purposes. One of the most common uses is as a decorative item. Balloons are also used as signal devices, aiding rescuers in locating victims who are lost at sea or in the woods, for example. Illuminating a balloon from the inside or the outside will add to its decorative characteristics or will make it easier to spot from a distance. The prior art addresses the need for illuminated signal balloons.
In the prior art, a light is incorporated into a balloon, either powered by batteries carried aloft or by an external power source connected to the balloon by wires. U.S. Pat. No. 4,586,456 issued to Forward describes an illuminated balloon wherein the illumination is provided by a flashlight carried in a specially designed balloon. This approach requires a balloon large enough to carry aloft the batteries powering the light source as well as the light source itself. The need of the balloon to support the weight of the batteries is mitigated in U.S. Pat. No. 4,542,445 issued to Marletta, in which the power supply for the light is separate from the balloon, the two being connected by a power cord.
Situating the light source inside the balloon is problematic because it generally produces heat as well as light. The current technology consists of multiple incandescent sources housed within the balloon and powered from the ground by a cable which also serves as a tether. These sources are extremely inefficient operating at an average of around 20 Lumens/Watt. These sources also require extensive power and thermal management devices because of the high power levels they require. The excess heat generated affects the gas inside the balloon, increasing the pressure on the inner surface of the skin of the balloon. It may also affect the balloon skin itself and other components within the balloon.
Moreover, a power cord itself presents a significant danger due to the impressed voltage and the current supplied by the power source. For example, during moderate to extreme wind conditions, the power cord could come into contact with combustible materials, or with people such as a rescuer or the victim, posing an inherent risk of fire or electric shock.
The problem of heat generated within the balloon, and the danger presented by a power cord, can both be circumvented through the use of fiber optic materials to deliver light from an external source to the interior of the balloon, whence it can be dispersed to provide effective illumination. U.S. Pat. No. 5,166,470 issued to Tuttle and U.S. Pat. No. 4,787,575 issued to Stewart incorporate fiber optics to reduce the weight carried by the balloon. Stewart's disclosure shows that the fibers may be "splayed" to disperse light. This directed light, which is directed to the inside of the balloon, is dispersed by the balloon itself in the Stewart disclosure. Thus, in the Stewart invention, the balloon is limited in that its skin cannot be transparent, since it must scatter light incident on it from an optic fiber.
If sufficient light were dispersed in an effective manner, illuminated balloons using fiber optic technology could also provide functional illumination as well as merely decorative illumination. The remote arrangement would allow the energy consuming portion of the system to remain on the ground where weight, heat, control and shock are not issues. This would expand application of the illuminated balloons to hazardous environments including the interior of petroleum storage tanks, crash sites 30 or flammable material leaks. Thus it is desirable to provide a manner in which to disperse light from optical fibers used in an illuminated balloon.
When a lighter-than-air balloon is used for functional illumination, it is occasionally necessary to reel in the balloon's tether, as for example, when winds arise of greater strength than 2 to 3 on the Beaufort scale. Therefore, even with a safe, effective means to illuminate the balloon, it would be further beneficial to have the balloon retractable in windy conditions.
U.S. Pat. No. 4,416,433 issued to Bellina describes a retractable tether in combination with a signal balloon. In that reference, it is up to the user to determine whether the balloon should be retracted. It is also up to the user to effect the retraction. This system requires the user's constant attention to the balloon's circumstances which is arguably a waste of time. Thus, it would be beneficial to automatically sense wind conditions to alert the user to the need for retraction of the tether; however, it would also be beneficial for such retraction to take place automatically, if desired by the user.